It’s become commonplace in the NFL for players who make a big play to spin the ball on the ground in celebration. But this year, players are being warned that there’s a fine line between celebrating and taunting — and if they cross that line, it’s a 15-yard penalty.

Reports today from members of the media at Vikings camp and Panthers camp indicate that referees working training camps are warning players that they’ll be penalized if they taunt opponents by spinning the ball.

This is not a new rule: The 2012 official playing rules listed examples of taunting, saying, “These acts include but are not limited to: sack dances; home run swing; incredible hulk; spiking the ball; throwing or shoving the ball; pointing; pointing the ball; verbal taunting; military salute; standing over an opponent (prolonged and with provocation); or dancing.”

But the fact that officials at two different training camps made a specific point of mentioning spinning the ball suggests that officials will be stricter about enforcing that rule this year than they were last year.

One player, Panthers receiver Steve Smith, even said he’s working on ways to continue his ball-spinning celebrations while staying within the rules. Smith, and every other NFL player, would be wise to err on the side of caution. Players may enjoy spinning the ball to celebrate, but no celebration is worth 15 yards.

It’s true that no celebration is worth 15 yards, but why ban them outright? Seems the NFL truly is becoming the No Fun League.